re-enable VAO with better workaround

src/mol-gl/webgl/extensions.ts

@@ -4,7 +4,7 @@
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  */
 
-import { GLRenderingContext, COMPAT_instanced_arrays, COMPAT_standard_derivatives, COMPAT_vertex_array_object, getInstancedArrays, getStandardDerivatives, COMPAT_element_index_uint, getElementIndexUint, COMPAT_texture_float, getTextureFloat, COMPAT_texture_float_linear, getTextureFloatLinear, COMPAT_blend_minmax, getBlendMinMax, getFragDepth, COMPAT_frag_depth, COMPAT_color_buffer_float, getColorBufferFloat, COMPAT_draw_buffers, getDrawBuffers, getShaderTextureLod, COMPAT_shader_texture_lod, getDepthTexture, COMPAT_depth_texture, COMPAT_sRGB, getSRGB, getTextureHalfFloat, getTextureHalfFloatLinear, COMPAT_texture_half_float, COMPAT_texture_half_float_linear, COMPAT_color_buffer_half_float, getColorBufferHalfFloat } from './compat';
+import { GLRenderingContext, COMPAT_instanced_arrays, COMPAT_standard_derivatives, COMPAT_vertex_array_object, getInstancedArrays, getStandardDerivatives, COMPAT_element_index_uint, getElementIndexUint, COMPAT_texture_float, getTextureFloat, COMPAT_texture_float_linear, getTextureFloatLinear, COMPAT_blend_minmax, getBlendMinMax, getFragDepth, COMPAT_frag_depth, COMPAT_color_buffer_float, getColorBufferFloat, COMPAT_draw_buffers, getDrawBuffers, getShaderTextureLod, COMPAT_shader_texture_lod, getDepthTexture, COMPAT_depth_texture, COMPAT_sRGB, getSRGB, getTextureHalfFloat, getTextureHalfFloatLinear, COMPAT_texture_half_float, COMPAT_texture_half_float_linear, COMPAT_color_buffer_half_float, getColorBufferHalfFloat, getVertexArrayObject } from './compat';
 import { isDebugMode } from '../../mol-util/debug';
 
 export type WebGLExtensions = {
@@ -73,11 +73,7 @@ export function createExtensions(gl: GLRenderingContext): WebGLExtensions {
         // - can't be a required extension because it is not supported by `headless-gl`
         console.log('Could not find support for "blend_minmax"');
     }
-    // TODO: revisit
-    // switch off VAO support for now
-    // - https://bugs.chromium.org/p/angleproject/issues/detail?id=6599
-    // - https://bugs.chromium.org/p/chromium/issues/detail?id=1272238
-    const vertexArrayObject = null; // getVertexArrayObject(gl);
+    const vertexArrayObject = getVertexArrayObject(gl);
     if (isDebugMode && vertexArrayObject === null) {
         console.log('Could not find support for "vertex_array_object"');
     }

src/mol-gl/webgl/resources.ts

@@ -133,7 +133,7 @@ export function createResources(gl: GLRenderingContext, state: WebGLState, stats
             return wrap('texture', createTexture(gl, extensions, kind, format, type, filter));
         },
         vertexArray: (program: Program, attributeBuffers: AttributeBuffers, elementsBuffer?: ElementsBuffer) => {
-            return wrap('vertexArray', createVertexArray(extensions, program, attributeBuffers, elementsBuffer));
+            return wrap('vertexArray', createVertexArray(gl, extensions, program, attributeBuffers, elementsBuffer));
         },
 
         getByteCounts: () => {

src/mol-gl/webgl/vertex-array.ts

@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2018-2020 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2018-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  */
@@ -8,6 +8,7 @@ import { Program } from './program';
 import { ElementsBuffer, AttributeBuffers } from './buffer';
 import { WebGLExtensions } from './extensions';
 import { idFactory } from '../../mol-util/id-factory';
+import { GLRenderingContext } from './compat';
 
 const getNextVertexArrayId = idFactory();
 
@@ -40,7 +41,7 @@ export interface VertexArray {
     destroy: () => void
 }
 
-export function createVertexArray(extensions: WebGLExtensions, program: Program, attributeBuffers: AttributeBuffers, elementsBuffer?: ElementsBuffer): VertexArray {
+export function createVertexArray(gl: GLRenderingContext, extensions: WebGLExtensions, program: Program, attributeBuffers: AttributeBuffers, elementsBuffer?: ElementsBuffer): VertexArray {
     const id = getNextVertexArrayId();
     let vertexArray = getVertexArray(extensions);
     let vertexArrayObject = getVertexArrayObject(extensions);
@@ -68,6 +69,13 @@ export function createVertexArray(extensions: WebGLExtensions, program: Program,
         },
         destroy: () => {
             if (destroyed) return;
+            if (elementsBuffer) {
+                // workaround for ANGLE/Chromium bug
+                // - https://bugs.chromium.org/p/angleproject/issues/detail?id=6599
+                // - https://bugs.chromium.org/p/chromium/issues/detail?id=1272238
+                vertexArrayObject.bindVertexArray(vertexArray);
+                gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, null);
+            }
             vertexArrayObject.deleteVertexArray(vertexArray);
             destroyed = true;
         }